2012 Ill inois
Forest Health Highlights
Prepared by Fredric Miller, Ph.D. IDNR Forest Health Specialist, The Morton Arboretum, Lisle, Illinois
Table of Contents
I.
Illinois’s Forest Resources
1
II.
Forest Health Issues: An Overview
2-6
III.
Exotic Pests
7-10
IV.
Plant Diseases
11-13
V.
Insect Pests
14-16
VI.
Weather/Abiotic Related Damage
17
VII.
Invasive Plant Species
17
VIII. Workshops and Public Outreach
18
IX.
18-19
References
I. Illinois’ Forest Resources
Illinois forests have many recreation and wildlife
benefits. In addition, over 32,000 people are
employed in primary and secondary wood processing
and manufacturing. The net volume of growing stock has
Figure 1. Illinois Forest Areas
increased by 40 percent since 1962, a reversal of the trend
from 1948 to 1962. The volume of elms has continued to
decrease due to Dutch elm disease, but red and white oaks, along with black walnut, have increased by 38
to 54 percent since 1962.
The area of forest land in Illinois is approximately 5.3 million acres and represents 15% of the total land
area of the state (Figure 1). Illinois’ forests are predominately hardwoods, with 90% of the total timberland
area classified as hardwood forest types (Figure 2). The primary hardwood forest types in the state are oakhickory, at 65% of all timberland, elm-ash-cottonwood at 23%, and maple-beech which covers 2% of
Illinois’ timberland.
.
1
F
o
r
e
s
t
MERALD ASH BORER (EAB) TRAP TREE MONITORING PROGAM
With the recent (2006) find ofMajor
emerald ash
borer (EAB)
in northeastern Illinois and subForest
Types
sequent finds throughout the greater Chicago metropolitan area, and as far south as
Bloomington/Chenoa, Illinois area, prudence strongly suggests that EAB monitoring is
needed for the extensive ash containing forested areas associated with Illinois state parks,
U.S. Army Corps of Engineers (USACE) lands, and the Shawnee National Forest (SNF).
Beginning in early July, 2008 trap trees were established at USACE lands at Carlyle,
Renwick, and Shelbyville Lakes, Hazlet, Murphysboro, and Giant City state parks, and at
the Garden of the Gods and Lake Glendale recreational use areas in the SNF. EAB trap
trees were established using the USFS EAB trap tree guidelines. Where possible,
trees in
Other
full sun were selected and at or near sites where EAB would most likely appear
(i.e.
Maple-Beech
campgrounds due to importation of firewood). In addition, we made every effort to se-
Elm-Ash-Cottonwood
T
y
p
e
Oak-Hickory
0
10
20
30
40
50
60
70
Percent of Total Timberland
Figure 2. Major forest types by percent of total timberland. Source: Illinois’ Forest
2005, NRS-29.
II. Forest Health Issues: An Overview
2012 ILLINOIS FOREST HEALTH HIGHLIGHTS
Arthropod Pests: Overall, the 2012 growing season was relatively quiet with no serious arthropod pest outbreaks with the exception of outbreaks of Gouty Oak Gall (GOG) on pin and shingle
oaks (Quercus palustris and Q. imbricaria) in central, western, and southern Illinois.
2
Gouty Oak Gall (GOG)
Gouty oak gall (GOG) is a woody gall that forms on small twigs and branches of scarlet, red, pin, and black
oaks (Quercus spp). The tiny native wasps, Callirhytis cornigera and C. quercuspunctata are responsible for
forming the galls (Figures 3 and 4) (10).
Like most gall-forming wasps, their lifecycles can be rather complex and complicated and GOG is no exception. Adults emerge in May and June, and lay eggs in major veins of oak leaves. GOG larvae form blister-like
galls with adults emerging in July. After mating, the adult female lays eggs in young oak twigs. Young
GOG’s appear as small, brown marbles which grow to two inch diameter brown galls. Later, adults emerge
from the gall completing the two-year lifecycle. (Figures 3 and 4).
Galls can be physically removed on small trees in the northern part of the insect’s range (northern Illinois), but
in southern Illinois, galling can be quite heavy and pruning may not be practical especially on large trees.
Heavy galling can cause death of twigs and branches, but generally does not kill a mature, healthy tree (10).
Heavy galling was observed in 2012 along the I-57 corridor south of I-70 (Effingham, Illinois) as far south as
the Dixon Springs area; between the I-57 and I-55 corridors from the Shawnee National Forest (SNF) north to
I-70; and west from Springfield along I-74 to the Mississippi River. Heavy GOG populations and tree death
were observed in south-central Illinois (Eldon-Hazlett and S. A. Forbes State Parks) as well as in the Springfield, Illinois area. GOG-affected trees were in all stages of decline from newly infested trees to dead trees.
Stress agents, such as drought, soil compaction, and poor drainage are probably the predisposing agents for
extensive dieback and death of pin oaks in south central Illinois, but death of individual branches by GOG was
evident. Further study is needed to determine the contributing factor(s) for extensive death of oaks in the affected areas.
Figure 3. Heavy infestation of GOG
Figure 4. Close up of GOG
3
Plant Diseases:
Foliar, root rot, vascular, decline, and canker diseases. Overall, disease incidence was atypical for 2012.
The early spring warm temperatures and below normal precipitation mitigated most foliar diseases. Stress related diseases like Cytospora, Botryosphaera, Thyronectria, and Fusarium cankers, oak wilt, and white pine
decline were more prevalent particularly later in the season as severe to extreme drought persisted.
Phytophthora root rots were present probably due to overwatering, poor drainage, and wrong plant siting.
Phomopsis tip blight of juniper and arborvitae was observed statewide (1, 11)
Ash Decline and Dieback. Considerable ash (Fraxinus spp.) decline (both green and white ash) continued to
be observed along the I-57 corridor south of I-70 to extreme southern Illinois (Dixon Springs area). Declining
ash were also observed earlier in the season (early June) along the I-64 corridor from south central Illinois
(Mt. Vernon area) west to the East St. Louis, IL. Most trees showed thinning canopies and dieback. Death
was also a common symptom. Trees were examined periodically throughout the summer, but there was no
evidence of EAB. This trend has been going on since 2008 and may be caused by ash decline and/or ash
yellows. Luley, et al. (1994) documented an outbreak of ash yellows in this geographic area.
More specifically, ash decline was specifically noted in east central Illinois (Kickapoo S.P.) in early June.
On-site interviews with IDNR personnel indicated ash trees had been declining for several years. Extensive
dieback (50% or greater) was observed in mid-July. Ash decline was also observed in other areas of east
central and southern Illinois (Fox Ridge, S.A. Forbes, and Wayne-Fitzgerrell S.P.’s).
Pine Decline. IDNR district foresters reported cases of white pine (Pinus strobus) decline statewide particularly in western Illinois. In addition, dying and dead Scots (P. sylvestris) and Austrian (P. nigra) pines were
common, in both urban and forested areas. Individual trees were not specifically examined, but most contain
evidence of bark beetles and Carolina pine sawyer beetles, and probably died of pine wilt disease. The
droughts and hot weather of 2010 and 2011 followed by the severe and extreme 2012 drought continue to predisposed these trees to the above pests and diseases.
Oak Decline. In addition to oak trees infested with GOG, chlorotic oaks were observed along the Mississippi
River valley between Trail of Tears S.F. and Lake Murphsyboro S.P. in southeastern Illinois and in northwestern Illinois along the bluffs of the Mississippi River valley from the Fulton-Savannah, Illinois corridor
north to the Elizabeth, Illinois area including Mississippi Pallisades S.P.
Weather and Abiotic Factors:
The 2012 winter was strange to say the least with extremely mild temperatures and below normal precipitation
(1) The 2012 winter was marked by much less snowfall (Figure 5). Monthly average precipitation was below
the 74 year normal for February and March, 2012. (Figure 6).
4
Figure 5.: Cumulative snow fall for December—March, 2012 (1)
Figure 6: Winter precipitation for December – March, 2012 (1)
5
The 2012 winter was also warmer than normal for the months of December through March (Figure 7). Record
-breaking heat was experienced in March and greatly accelerated bloom times for many of plants. For example, lilac and viburnum that normally bloom in late April and into May started blooming in late March. Bud
break, flowering, and leaf emergence not only came early, but over a shorter period of time than usual.. Along
with accelerated plant phenology, insect development increased with insects emerging about four weeks earlier
than normal. All of this warm March weather was followed by a series of late spring frosts and freezes in
April and May. Fruit trees and other flowering plants were damaged and fruit production (especially apples)
were hard hit in the northern regions of Illinois. Forest species that were in the midst of leafing out were also
damaged.
Figure 7: Average winter temperatures for December – March, 2012 (1)
Dry weather continued throughout summer, 2012 resulting in one of the worst droughts since 1988. Areas of
southern Illinois experienced extreme drought while the rest of the state was under moderate to severe drought.
The effects of the drought included severe leaf scorch of maples, early leaf drop for honeylocust and elms, and
early fall color for most shadetree and forest species. It is expected that many trees species will continue to be
under stress going into the 2013 field season due to damage to find feeder roots and root hairs, and reduced
stored food. Stress related diseases (i.e. cankers and vascular diseases) and insects (i.e. wood borers and bark
beetles) will probably be more prevalent in 2013 and beyond on pre-disposed trees. Proper plant management
will be critical in assuring plants have a reasonable chance to recover and rebound from the 2012 drought.
6
Exotic Pests
The emerald ash borer (EAB) continues to spread throughout Illinois particularly to the west. New positive finds for 2012 include Knox, Henry, and Lee counties in western Illinois near the Quad City area. To
date, 40 Illinois counties are under quarantine and 29 counties have known EAB infestations (refer to Figure 8). Beginning in 2012, purple and green Lindgren funnel traps (LFT’s) were deployed in 60 Illinois
state parks forests, natural areas, seven county forest preserves districts, and on private property of forest
landowners. This is a change from using the purple panel traps in previous years.
The emerald ash borer (EAB) is a phloem feeding wood boring insect that kills
its host by destroying the vascular system
of the tree. Unlike many other borers,
EAB has the capability to attack both
healthy and stressed ash trees.
Asian Long-horned Beetle (ALB). To
date, no new sightings of ALB have
been discovered. The original ALB infested areas are no longer under quarantine and the Illinois quarantine is now
lifted since ALB has not been found
since 2007. Along with visual surveys,
newly developed ALB traps were deployed in 2012 in selected areas of seven
county forest preserves in northeast Illinois. Visual monitoring efforts are always on-going.
Figure 8. EAB Quarantine Map and New Finds
Brown Marmorated Stink Bug
(BMSB). This newest exotic insect pest
has been found in Illinois in Cook and
Kane counties as early as 2010. This insect has a broad range host including tree
fruits, vegetable, and woody landscape
plants (3). A BMSB pheromone trap was
deployed in 2012 in Will county at the
Joliet Junior College (JJC) Horticulture
Land Lab (HLL) as part of a statewide
monitoring program. To date, there
have been no new BMSB finds.
Viburnum Leaf Beetle (VLB). As reported in the 2009 Forest Health Highlights (FHH), the viburnum
leaf beetle (VLB) was found in 2009 in an urban Cook county landscape. The viburnum leaf beetle feeds
on a variety of commonly planted viburnums and has the potential to become a major pest of these ubiquitous woody landscape plants. The VLB was added to our
watch list. To date no new finding of the
7
VLB has been reported.
Chinese Long-horned Beetle (CLHB). Another invasive long-horned beetle, Hesperophanes campestris;
synonym Trichoferus campestris and similar to ALB appeared for the first time in 2009 near O’Hare airport
and in Crawford county in east central Illinois (Figure 9). Its arrival at O’Hare is not surprising since it is a
major point of entry, but the east central Illinois find is unsettling. The CLHB was captured near a palletmaking plant which is consistent with the movement of infested green wood and wood products. CLHB has
also been found near Minneapolis, MN and in Quebec, Canada. The insect is originally from Asia and parts of
Eastern Europe and spreads through movement of infested wood. It has a similar life cycle as the Asian longhorned beetle (ALB) and causes similar damage to trees. Preferred hosts of the CLHB are presented in Table
1 (9). In cooperation with APHIS, an intensive trapping, effort using 12 Unit LFT’s, was conducted in 2012
in 60 state parks, forests, natural areas, and the northeast Illinois seven (county forest preserve system. To
date, no new CLHB finds have been confirmed.
Table 1. Preferred hosts of the Chinese long-horned beetle (12)
__________________________________________________________________
Apple
Mulberry
Maple
Birch
Beech
Ash
Locust
Walnut
Larch,
Fir
Cedar
Oak
Willow
Elm
Cut wood of spruce and pine.
___________________________________________________________________
Figure 9. Adult Chinese Long-horned Beetle
Thousand Cankers Disease of Walnut (TCD)
To date, TCD has not been found in Illinois. Beginning in early summer, 2012, four unit LFT’s were deployed along with a newly developed pheromone for detection of the walnut twig beetle (WTB). Traps were
placed in 60 state parks, forests, natural areas, the seven county forest preserve system, private woodlots, and
wooded areas near mills (Figure 10). In addition to trapping, visual assessments of declining walnut trees, and
documentation of walnut plantings and walnut natural stands are being conducted and developed.
8
Figure 10. Distribution of LFT’s for 2012
Key: Blue symbols = EAB 12 Unit Green LFT’s; Red dot symbols = WTB 4 Unit Black LFT’s;
Orange diamond symbols = Hardwood Borers 12 Unit Black LFT’s
Sudden Oak Death (SOD). SOD is a deadly disease that
attacks primarily oaks, but also rhododendron, and other
woody ornamental trees and shrubs. The fungus causes
cankers on stems contributing to plant decline and eventual
death. Beginning in spring, 2012, a stream
baiting sampling program was conducted as per the USDA
-SOD protocol.. Another sampling period (October – November, 2012) has commenced. To date, no SOD inoculum has been found at the Illinois sampling site.
Dutch Elm Disease (DED). This vascular wilt disease has
been with us for decades and continues to kill American
and red elms throughout Illinois. Based on reports provided by the University of Illinois Plant Clinic (UIPC) and
Morton Arboretum Plant Clinic (MAPC), DED cases continue to be a problem and levels were comparable to 2011
levels (1, 11).
Oak Wilt (OW). The dreaded oak wilt is found in every
Illinois county and has become a major urban and forest
tree disease. Reports for 2012 by the UIPC indicate that
2012 OW disease incidence was higher compared to previous years (11). It is very likely, that the 2012 drought contributed or even accelerated the development of OW in
pre-disposed trees.
Verticilium Wilt (VW). This very ubiquitous and opportunistic vascular wilt fungus was common in 2012 and at levels seen in previous years. Flooding and drought
over the last seven years including the severe 2012 drought has and will continue to pre-dispose woody plants
to VW. Sugar maple, red maple, ash, smoketree, Japanese maple, saucer magnolia, and
three-flowered
maple are just a few examples of VW susceptible hosts (3).
Bacterial Leaf Scorch (BLS). Bacterial leaf scorch resembles abiotic scorch, but is caused by a bacterium,
Xylella fastidiosa (Figure 11). It is thought to be spread by leafhoppers and spittlebugs (Figure 12). Tree hosts
include elm, hackberry, maple, mulberry, oak, sweetgum, sycamore, and planetree (Table 2) (5) Since 1999,
the UIPC records show that BLS has tested positive in 10 Illinois counties stretching from Jefferson, Madison,
and St. Clair counties in southern Illinois through parts of central Illinois (i.e. Sangamon, Champaign, Douglas
-Moultrie, Iroquois), north to Cook and DuPage counties, and to Jo Daviess county in extreme northwest Illinois (11). With the exception of Champaign county with 40 positive samples, the remaining 9 counties have
had 1-3 positive cases confirmed. In terms of hosts, BLS has been found in bur, northern red, pin, white,
swamp white, and shingle oaks from 1999-2008. In 2008, BLS was found in seven oak positives including
northern red, swamp white, pin and several unidentified oak species. Eleven BLS samples submitted in 2010
to the MAPC. Of those 11 samples, two were positive, one inclusive and eight were negative (1). The positives were found on oaks growing in DuPage and Cook9counties.
In 2011, a total of 22 trees were tested for Xylella fastidiosa. One sample, taken from an American elm (U.
americana), tested positive (Cook county), and six were elevated and inconclusive. Eleven (11) samples were
taken from trees growing at The Morton Arboretum. Additional samples were received from western and
northwestern suburbs of Chicago, and western Illinois, but were negative (1). Reports received from the
UIPC indicate BLS symptoms were more pronounced in 2012 probably due to drought stress.
Figure 11. Bacterial leaf scorch symptoms
Figure 12. Spittle bug
Table 2. Tree species known to be susceptible and not susceptible to BLS (5)
Susceptible Species
Non-Susceptible Species (Based on Observations)
__________________________________________________________
American elm
Gingko
Hackberry
Red maple
Silver maple
Sugar maple
Black oak
Bur oak
English oak
Northern red oak
Pin oak
Swamp white oak
White oak
American sweetgum
American sycamore
European black alder
Northern catalpa
Kentucky coffeetree
Amur cork tree
Chinese elm
Sugar hackberry
Shagbark hickory
Shellbark hickory
Pignut hickory
Katsuratree
Littleleaf linden
Cucumbertree
Black maple
Chinkapin oak
Sawtooth oak
Common sassafras
Tulip tree
Japanese zelkova
__________________________________________________________________
10
Bur Oak Blight (BOB). Bur oak leaf blight is a fungal disease
that attacks bur oak (Quercus macrocarpa) with severe symptoms
occurring on Q. macrocarpa var. oliviformis (Figure 13). It has
been found in Kansas, Nebraska, Minnesota, Iowa, Wisconsin, Illinois and Missouri. In 2011, BOB was
found isolated from a tree in Winnetka, Illinois (north shore area of Chicago) and in 2012 from a single tree
in Lake County, Illinois.
IV. Plant Diseases
BOB is caused by the Tubakia sp fungus resulting in blighting of the tree over a period of years. It starts in
the lower portions of the tree and moves upward. Leaf symptoms usually do not show up until late summer
(Figure 14). Severely affected trees may die after protracted years of defoliation. Bur oaks growing in established savannahs and upland areas appear to be more vulnerable. Oaks growing in bottomlands and/or dense
forests appear to be less affected (4,12).
Figure 13. BOB tree symptoms
Figure 14. BOB foliar symptoms
Needle cast disease. Two very common diseases affecting conifers, Rhizosphaera needle cast and Diplodia
(i.e. Sphaeropsis) were present in 2012. Both of these fungal leaf diseases attack the needles of cone-bearing
tree species causing premature needle cast or a browning and/or death of the growing tip, respectively.
While not outright fatal, they stress the trees and reduce overall ornamental qualities and growth rates. Coupled with chronic drought, a deadly combination may result (1,11).
Stress-related canker diseases. Cytospora canker of spruce is definitely a stress related disease particularly
of Colorado blue spruce. Spruces are a common urban forest and landscape species. The cankers are initially found on the undersides of the branches and result from some type of stress. Spruce trees growing in
urban environments are very prone to this canker. While not fatal, the cankers cause branches to die distal to
the canker resulting in a loss of ornamental quality and landscape function (1). In addition, there has been an
increase of Thyronectria canker on honeylocust and the honey locust borer in areas of northeast Illinois. It is
anticipated that other cankers will make their appearance in 2013 and beyond due to the 2013 drought (1).
11
Hickory Decline. In recent years, reports of dieback and mortality of hickory have been reported in areas of
the upper Midwest (Figure 15). Bitternut hickory (Carya cordiformis) and shagbark hickory (C. ovata) appear
to be most affected. Symptoms include thinning canopies, dead branches, and eventually tree death (13).
Historically, death of hickory trees was attributed to the hickory bark beetle (Scolytus quadrispinosus)
following droughts. Recent research seems to indicate that hickory decline may include a complex of biotic
and abiotic factors such as bark beetles (Xylobiopsis basilaris and borers (Agrilus otiosus), and the fungus
Ceratocysis smalleyi. In some cases, Armillaria root rot fungus has been found associated with recently dead
trees (13).
Hickory decline and dieback is most common in overstocked stands. Current management practices include
sanitation by removing dead and dying trees to reduce bark beetle breeding habitat and insecticide applications
to the trunk of individual trees. Widespread use of insecticides for forest stands is not be economical nor
practical (13).
Figure 15. Hickory decline
12
Heterobasidion spp of red pine. The fungus is a root and basal stem rotting fungus that
colonizes cut stumps and then moves through root systems to adjoining trees. The fungus eventually colonizes
the lower stem leading to wind throw and death of affected trees. In the Midwest, white, red, and jack pines
are most susceptible (Figure 16). Thinned and/or harvested pine stands are prone to this disease. Prevention is
the best approach. Treating freshly cut stumps with a fungicide along with and good sanitation and
stump removal are important management tactics.
Aerial and ground surveys from 1962 to 1971 by Hanson and Lautz confimed Heterobasidion annosum being
present in southern Illinois. Since 1971, there is no record of further H. annosum surveys. Statewide surveys
will resume in 2013.
Figure 16. Distribution of Heterobasidion annosum or irregulare in the Northeastern, USA
13
V. Insect Pests
Bark Beetles (BB) and Wood-borers (WB). Bark beetles attack primarily stressed trees including both hardwoods and conifers. Prolonged drought or a variety of abiotic and biotic stresses may pre-dispose trees to bark
beetle attacks.
Based on field observations and in conversations with green industry members and foresters, 2012 appeared to
a “normal year” for bark beetle activity. No major bark beetle outbreaks were observed or reported. However,
that may change very quickly starting with the 2013 field season. Due to extremely dry conditions, trees are
still stressed and may be attacked by bark beetles and/or borers. Weaken trees may lack the ability to fight off
these attacks and succumb.
In addition, engraver beetles and the Zimmerman pine moth continue to be chronic problems for many of our
urban forest conifer species particularly Scots, Austrian pine, and mugho pines. As above, both of these insect
pests tend to attack stressed conifers growing on poor sites (poor drainage) along with drought stress, soil compaction, construction damage, etc.
Expanding on 2011 trapping efforts, 12 unit LFT’s were placed in 60 state parks, forests, and natural areas, on
private land, and near wood mills during the 2012 field season. The results of these trapping efforts are presented in Table 3. Bark beetles, (conifer, engraver, and hardwood insect species) make up the majority of insects trapped. Long-horned beetles and flat-headed borers accounted for only 5% of trap catches.
Table 3: Summary of Lindgren Funnel Trap (LFT) catches for the 12 Unit EAB trap, 12 Unit Exotic
Bark Beetle trap, and 4 Unit WTB trap (May – September, 2012)
TRAP TYPE
N
TRAP SPECIMENS
EAB
Bark Beetles1
Longhorn
Flat-Headed
Beetles
Borers
_________________________________________________________________________________________
EAB LFT
Percent of Total
60
Weevils
3
(<1%)
4, 12 Unit LFT
60
4,203
93
184
45
Percent of Total
(73%)
(2%)
(4%)
(1%)
___________________________________________________________________________________________
1
Bark beetles include members of the Scolytus and Ips genera
Fall Webworm (FWW) and Eastern Tent Caterpillar (ETC). Small scattered pockets of fall webworm
(FWW) and eastern tent caterpillar (ETC) nests were seen at state parks and forests in southeastern (Lincoln
Trail S.P.) and southern Illinois (Lake Murphysboro and Pyramid S.P’s). Populations were comparable to previous years.
14
Japanese Beetle (JB). Japanese beetle was evident throughout the state , but defoliation was sporadic and not
nearly as extensive as in previous years. Heavy Japanese beetle damage (50-75% defoliation) was common on
lindens and crabapples throughout central, western, and southern Illinois (south of I-80 between the I-57, I-39,
and I-55 corridors, and north and south between the I-70 and I-80 corridors).
Elm Flea Weevil (EFW). The European flea weevil (EFW) (Orchestes alni) has been a pest in the upper
Midwest since 2003, but has been in the U.S. since 1982. The EFW is a very tiny insect (1/16th inches long)
with the characteristic long snout. (Figure 17). Adults are reddish-brown with black heads. Adult EFW’s
emerge in May and early June and begin feeding on young leaves chewing small holes in the leaf (Figure 18).
Adult females lay eggs and the young larvae begin mining the leaf-tip eventually becoming a blotch-like mine.
Larvae pupate within the leaf and emerge as a adults in mid to late summer. Adults over winter in under loose
bark and in litter under infested trees (2). EFW feeding damage should not be confused with the elm leaf miner (Kaliofenusa ulmi) which is a blotch-mining sawfly. While the adult elm leafminer (ELM) emerges about
the same time as the EFW there are subtle differences in larval feeding and biology. ELM larvae typically
form blotch-like mines throughout the leaf in contrast to the leaf tip mines associated with EFW larvae. Also,
by mid-June, mature ELM larvae drop from the leaf and enter the soil to pupate. Adult emergence does not
occur until the following spring with one generation per year.
Figure 17. Adult flea weevil
Figure 18. Adult flea weevil feeding damage
Larval and adult feeding is usually considered an aesthetic issue, but coupled with heavy Japanese beetle feeding damage, preferred hosts can be completely defoliated by mid to late summer.
Research conducted at The Morton Arboretum (7, 8) and by Condra et al. (2010) indicate that U. pumila
(Siberian elm) and ‘Homestead’ elm are the most susceptible to EFW feeding damage. In addition, long term
field feeding preference studies conducted at The Morton Arboretum have indicated that elm hybrids with
Siberian elm and U. carpinifolia parentage are strongly preferred by EFW (8). Refer to Table 4 for a listing of
highly preferred hosts and host preference by geographic origin.
15
Table 4. Summary of elm flea weevil (EFW) medium to heavy feeding damage on elms (Ulmus spp) and
very low to low feeding damage, and by geographic origin (The Morton Arboretum (2004-2009).
Elm Biotype
Elm Biotype
(Medium to Heavy)
(Very Low to Low)
________________________________________________________________________
U. laevis
U. propinqua var. suberosa
U. Morton Glossy ‘Triumph’
U. glabra
U. davidiana var. manshurica
U. alata
U. americana f. pendula
U. macrocarpa
U. lamellose
U. thomasii
U. castaneifolia
U. crassifolia
U. foliaceae
U. parvifolia var. coreana
U. procera
U. americana ‘Moline’
U. berganniana
U. ‘Morton Plainsman x U. parvifoia
U. pumila
U. japonica x U. wilsoniana
U. davidiana x U. pumila
U. pumila x U. americana
U. pumila x U. rubra
‘Sapporo Autumn Gold’ (U. pumila)
U. carpinifolia x U. pumila
U. carpinifolia hybrids
Field Feeding Damage Rating (FFDR)1
Origin
__________________________________________________________________________________________________________________
 Asia
2.2
 Complex Asian hybrids
2.0
 Europe
3.9
 North America
0.4
 Zelkova spp.
0.7
 Simple and complex hybrids of U. pumila and U. carpinifolia
4.5
__________________________________________________________________________
1
FFDR is based on a scale of: 0=no feeding damage; 1=very low; 2=low; 3=moderate; 4=heavy; and 5=severe
feeding damage
16
VI. Weather/Abiotic Related Damage
Based on the Palmer Drought Index, severe to extreme drought affected about 34 percent of the contiguous
United States as of the end of October 2012, a decrease of about 4 percent from September. Areas of southern
Illinois were under exceptional drought for most of the summer, and central and northern Illinois experienced
severe to extreme drought.
Drought related symptoms of scorch, early leaf drop, dieback, and early fall color began by mid summer and
were common on willow, cottonwood, maple, honeylocust, elm, ash, and conifers. Aerial flyovers in August
and early September revealed that early fall color was much more pronounced in 2012 compared to the same
time in 2011.
What little precipitation that was received usually came down in heavy downpours associated with thunderstorms. Small pockets of storm damage were observed in southern Illinois consisting of broken limbs, and a
few down trees. Similar damage was observed in the Chicago area in June and early July due to very localized
severe storms of short duration.
Fall precipitation has been more consistent and is helping replenish soil moisture levels. It will be important
not to forget the 2012 drought as we enter the 2013 growing season. Many woody plant species suffered significant damage to fine roots and root hairs. This “infrastructure” will have to be replaced and repaired which
will require good winter and spring precipitation. It could take several growing seasons for plants to return to
normal even under optimum growing conditions. Stressed plants will be pre-disposed to secondary agents
such as wood-boring insects and disease-causing cankers, and other stress-related pathogens. Good plant
health care practices will be important in helping these plants survive and recover.
VII. Invasive Plant Species
No formal statewide surveys or studies were conducted in 2012 related to invasive plant species.
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VIII. Professional Training Clinics and Public Outreach
Three diagnostic training workshops were conducted in late summer and early fall, 2012; one at The Morton
Arboretum outside Chicago a second in Murphysboro, Illinois, and a third in Springfield, Illinois. Attendees
included commercial and municipal arborists, IDNR district foresters, consultants, master gardeners, and natural resource managers. Workshop participants received classroom instruction and hands on field training on
proper pest and disease identification, diagnosis, and sampling techniques. Training topics included TCD,
BLS, BOB, common Arthropod pests, and abiotic diseases.
Public outreach events for 2012 included town hall meetings, an EAB symposium, and seminars, addressing
management options for EAB and how individual homeowners and communities can prepare for tree mortality
and subsequent effects of EAB on urban forests and shade trees.
IX. References
1. Adams, S., 2012. The Morton Arboretum Diagnostic Plant Clinic and Plant Health Care Reports. The
Morton Arboretum, Lisle, Illinois.
2. Condra, J., C. Brady, and D.A. Potter. 2010. Resistance of landscape suitable elms to Japanese beetle,
gall aphids, and leaf miners, with notes on the life history of Orchestes alni and Agromyza aristata in Kentucky.
3. Gill, C. 2010. Plant Health Progress. Pennsylvania State University (PSU) (17 October 2010).
4. Harrington, T. 2011. It looks like bur oak blight (BOB) really isn’t new. Iowa State University, Horticulture Home Pests News. February, 2011
5. Hartman, J. 2007. Bacterial leaf scorch. PPFS-OR-W-12. University of Kentucky Cooperative Extension Service
6. Luley, C., M. Mielke, J. Castello, J. Carlson, and J. Appleby. 1994. Ash crown condition and the incidence of ash yellows and other insects and diseases in Illinois, Iowa, Missouri, and Wisconsin. Plant Disease.
76: 1209-1212.
7. Miller, F. 2000. Insect resistance of elm genotypes. [Proceedings of the First International Elm Conference.] Entitled: The Elms: Breeding; Conservation, and Disease Management. ed. C. Dunn. pp. 137-154.
8. Miller, F. (Unpublished). Observations on the preference and susceptibility of elms (Ulmus spp.) for feeding by the elm flea weevil.
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9. Minnesota Department of Agriculture. 2011. Invasive pest alert: Chinese longhorned beetle.
10. Nixon, P. 2001. Gouty and horned oak galls. University of Illinois, Home, Yard, and Garden Newsletter. Urbana-Champaign, Illinois.
11. Pataky, N. and S. Porter. 2008-2012. Woody Plant Disease Updates. University of Illinois Plant Clinic
(UIPC). Urbana, Illinois.
12. Pokorny, J. and T. Harrington. 2011. Bur oak blight. Pest Alert-NA-PR-02-11. USDA Forest Service.
13. Wisconsin DNR. 2007. Hickory dieback and mortality in Wisconsin.
PLEASE NOTE: The data presented in this summary are not to be considered to be comprehensive nor all
inclusive studies. The narrative reported here is based on visual and observational surveys by Dr. Fredric
Miller, IDNR Forest Health Specialist, IDNR Forest Health field technicians, IDNR district foresters, Stephanie Adams of The Morton Arboretum Plant Diagnostic Clinic, informal conversations with consultants and
members of the green, natural resources, and forest industries.
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